Apparatus and method for ice and snow removal

ABSTRACT

An object such as a trailer or building has a flexible cover which normally protects the object, but on which unwanted surface material such as snow and ice may build up. Stowed between the object and the cover is an inflatable air bag. When it is desired to remove accumulated surface material, a fixture means is released to allow limited movement of the cover. The air bag is inflated from its stowed generally flat state and, in its inflated state, has a profile tending to dislodge the surface material. Once the surface material has been dislodged, the air bag is deflated and stowed, and the fixture means is secured.

CROSS REFERENCE TO RELATED PATENTS

This patent application claims priority under 35 USC §119 to a provisionally filed patent application entitled ICE AND SNOW REMOVER FOR VEHICLES, having a filing date of 11-Feb.-2008, and a Ser. No. 61/027662, and to a provisionally filed patent application entitled APPARATUS AND METHOD FOR ICE AND SNOW REMOVAL, having a filing date of 6-May-2008, and a Ser. No. 61/050654.

TECHNICAL FIELD OF THE INVENTION

This invention relates to a method and apparatus for clearing snow, ice or other adherent or loose material from a base object such as a truck or trailer. In this disclosure, it will be understood that any reference to trailers encompasses any structure having a surface from which a layer of material is to be cleared, such structures including vehicles and buildings. In addition, any reference to removing ice from surfaces will be understood to encompass removal of snow and other adherent or loose materials from surfaces.

If ice is left on a trailer roof while a vehicle is in use, there is a danger to traffic using the highway if the ice is blown off or slides onto another vehicle. In addition the presence of unwanted ice is costly and polluting since more fuel is used to haul the extra weight.

DESCRIPTION OF RELATED ART

Current methods of clearing ice from trailer roofs involve either manual use of a shovel, or a brush or scraper system attached between two poles.

Manual shoveling of snow or ice is not only laborious and time consuming, but is also dangerous as it can involve heights of over 4 meters. Shoveling snow and ice at such heights, in cold temperatures, and on top of roofs that are most often made of fiberglass is hazardous and will breach safety laws unless proper equipment, such as cat walks and fall arrest systems, is used. This makes it impractical to most companies, owners, and drivers.

Alternative systems consist of two poles between which a brush or scraper arrangement is mounted. In use, a trailer is moved to the system site and between the poles where the brush or scraper arrangement is actuated. Traveling to the system site may be inconvenient, impractical, or unavailable. In addition, such systems cost in the range of $45,000-$100,000 and take up space in trucking yards. This makes them unattractive and impractical for smaller trucking companies. Larger companies that can afford such systems and have the necessary yard space still run into problems because trucks and trailers are often left at a customer's yard for loading and unloading. The same is true if a truck operator has a rest, for example, at a truck stop. Snow and ice may accumulate on the trucks and trailers away from their yards and the pole system for scraping or brushing away the snow and ice is therefore inaccessible.

SUMMARY OF THE INVENTION

According to the invention, there is provided apparatus for clearing surface material which makes use of a truck or trailer's flat or curved roof as a support basis for waterproof and weather-resistant flexible cover. Underneath the flexible cover is located an air bag, or multiple air bags, that can be inflated with a gaseous medium, such as compressed air, or exhaust from the truck. The gaseous medium inflates the air bag(s), which in turn forces the flexible cover into a shape different from that which it normally has in a rest position. The movement of the flexible cover to a raised, contoured profile is such as to force water, snow, ice or other surface material to fall away from the roof of the truck or trailer and onto the ground. The air bag(s) including at least some of the equipment necessary to inflate them are protected from the elements by the outer flexible cover. Once the air is released from the air bag(s), they deflate and revert to a flat resting position. Ropes or cables are attached on the flexible cover to enable the flexible cover to be pulled back to its resting position so that it holds its shape when the truck or trailer is being driven along the highway. The ropes can be elasticated or can be attached to traces which are easily accessed by the vehicle operator.

In operation, when the vehicle operator notices ice or snow on top of the truck or trailer, or as a part of a regular inspection routine, he releases cables or ropes that normally hold the outer cover in place so as to permit a certain amount of movement of the cover. The vehicle operator then starts the supply of the gaseous medium to inflate the air bag(s). This can for example use a compressor or the vehicle's exhaust system. The bag(s) inflate, raising the outer cover to a different shape than its resting shape to throw water, snow, and ice off the roof. After the roof is clear, the vehicle operator shuts off the supply of gaseous medium to the air bag(s).

Following use, the vehicle operator actuates a release valve to allow the air bag(s) to fully deflate. An auxiliary pump can also be used to extract air from the bags if required. The vehicle operator then reels in the ropes or cables attached to the flexible cover and ties the ropes or cables down to fix the cover in its resting position and to ensure the cover does not present a hazard by flopping around in the wind as the truck or trailer is being driven. A hand winch can be used to reel in the ropes or cables and the rope or cable ends are locked into position once the cover is tied down.

The system can be built of light materials and is typically of low profile occupying something less than an inch in height in normal driving mode. The added weight and wind resistance are therefore small and have minor impact on fuel economy, especially in comparison to carrying snow and ice. The flexible cover material can be made of UV resistant material to reflect sunlight off the roofs of trucks and trailers so as to aid in the summer to cool off the truck and trailers.

BRIEF DESCRIPTION OF THE DRAWINGS

For simplicity and clarity of illustration, elements illustrated in the following figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to other elements for clarity. Other advantages, features and characteristics of the present disclosure, as well as methods, operation and functions of related elements of structure, and the combinations of parts and economies of manufacture, will become apparent upon consideration of the following description and claims with reference to the accompanying drawings, all of which form a part of the specification, wherein like reference numerals designate corresponding parts in the various figures, and wherein:

FIG. 1 shows a top view of a trailer and air bags forming part of an ice removal assembly according to an embodiment of the invention.

FIG. 2 shows a side view of a trailer and part of an ice removal assembly according to one embodiment of the invention.

FIG. 3 shows a side view of a trailer and part of an ice removal assembly according to another embodiment of the invention.

FIG. 4 shows a side view of a trailer and part of an ice removal assembly according to a further embodiment of the invention.

FIG. 5 shows a top view of a trailer and air bags forming part of an ice removal assembly according to a further embodiment of the invention.

FIG. 6 shows a top view of a trailer and air bags forming part of an ice removal assembly according to another embodiment of the invention.

FIG. 7 shows a top view of a trailer and an air bag forming part of an ice removal assembly according to another embodiment of the invention.

FIG. 8 shows an end view of a trailer and part of an ice removal assembly according to another embodiment of the invention.

FIG. 9 shows a top view of the embodiment of FIG. 8.

FIG. 10 shows an end view of a trailer and part of an ice removal assembly according to another embodiment of the invention.

FIG. 11 shows an end view of a trailer and part of an ice removal assembly according to a further embodiment of the invention.

FIG. 12 shows an end view of a trailer and part of an ice removal assembly according to yet another embodiment of the invention.

FIGS. 13 and 14 show end views of two forms of cover for an ice removal assembly according to another embodiment of the invention.

FIG. 15 shows an end view of a trailer and part of an ice removal assembly according to a further embodiment of the invention.

FIG. 16 shows an end view of a trailer and part of an ice removal assembly according to an embodiment of the invention.

FIG. 17 shows an end view of one form of cover for an ice removal assembly according to an embodiment of the invention.

FIG. 18 shows an end view of another form of cover for an ice removal assembly according to an embodiment of the invention.

FIG. 19 shows an end view of a further form of cover for an ice removal assembly according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

One exemplary embodiment of apparatus according to the invention is shown in the top elevation of FIG. 1. In the figure, the various elements of the apparatus are shown exposed, although it will be understood that certain elements will be covered by other elements when the system is in use. A length of aircraft cable 3 extends between front and rear ends of a trailer 12 and is fixed at each end. A cover 10 extends from one side of the trailer roof where it is tied off by cables or ropes (not shown) to the other side of the roof where the aircraft cable 3 is mounted. The cover 10 is folded around the aircraft cable so that a marginal section 11 approximately 15 inches in width is folded under the main part of the cover. A first series of D-rings 4 is mounted along the edge of the cover and a second series of D-rings 6 is mounted to the vehicle roof near the opposite side of the roof. A control rope 13 is threaded back and forth between alternating pairs of D-rings and is tied off at the front end of the vehicle.

In normal driving, the control rope 13 is winched tight and supplementary tie downs (not shown) attached at front, back and sides of the cover 10 ensure the cover is fixed tightly against the vehicle roof to protect the system elements under the cover.

In ice clearing mode, the control rope or cable 13 and the supplementary tie downs are released. As a series of airbags 22 are filled with air, the cover 10 stretches and the folded section 11 unfurls as the cover 10 rolls around the aircraft cable 3. The elements of the system are dimensioned so that in the fully stretched position, the side edge of the cover 10 is next to the aircraft cable 3. Subsequently, as the airbags 22 deflate, the vehicle operator actuates the control rope or cable 13 to bring the folded cover section 11 back and underneath the main part of the cover 10.

As shown in FIG. 1, three air bags 22 are used. Typically the bags will be of a standard size such as 8 feet by 4 feet regardless of the size of the truck or trailer so that they can be mass produced without dependence on the dimensions of the vehicle on which they will be deployed.

In a variation as shown in FIG. 2, one edge of a trailer cover 10 (not shown) is fixed along one top edge of trailer 12. A set of D-rings 4 is fixed along the opposite edge of the cover and a corresponding row of D-rings 6 is arrayed along the corresponding side of trailer 12 near its upper edge. A cable or rope 8 is laced through the opposed sets of D-rings. One end 7 of the cable or rope is anchored securely at the front of the trailer and the other end is attached at a winch or ratchet 9 at the other end of the trailer. The rope or cable is straightened under the action of the winch or ratchet to bring the sets of D-rings together and hold the cover and the underlying air bags in place.

In an alternative embodiment of the invention as shown in FIG. 3, one side (not shown) of trailer cover 10 is securely tied down at one side of trailer 12. An edge part 14 of the other side of the cover projects over the other side of the trailer by several inches and has a pole 16 stitched or otherwise fixed along the cover edge and running the length of the trailer. The pole has attached straps 18 which are connected to hand winches or ratchets 20 attached near the bottom of the trailer. Before inflating the air bags (not shown) to clear the trailer roof of ice and snow, the driver releases each of the winches or ratchets 20 to slacken off the straps 18. The bags are then inflated to clear the roof of snow and ice and, are subsequently deflated. The driver then reapplies the winches or ratchets to tighten the straps to secure the cover 10 for road travel.

In an alternative embodiment of the invention shown in FIG. 4, springs 22 are used in place of the hand winches or ratchets to permit a more automated operation. In such an embodiment, as bags are inflated, the springs are caused to extend. Then as the bags are deflated, acting through the straps 18, the springs pull the cover back to its rest position as they are restored to their unextended condition. In practice, the springs are mounted in protective housings to protect them from damage.

It will be understood that the cover and air bag assembly may have no value during the time that there is no risk of ice or other material building up on the trailer roof and, in fact, the assembly can become an inconvenience. At such times, as an alternative to removing the assembly parts from the trailer, the assembly can include a pouch (not shown) mounted to the body of the trailer. In such an arrangement, one edge of the cover is anchored at the pouch and a supplementary cable or rope arrangement is used to maneuver the cover and the air bags into the pouch. A compact storage arrangement extending along the side and/or front of the trailer means that the assembly does not take storage space either at the haulier's trucking yard or inside the trailer, which would displace paying cargo. The arrangement also protects the parts of the ice clearing assembly from exposure to the elements, so extending the life of the assembly parts.

A preferred source of gas to fill the bags is compressed air. Many trucks already have an engine-driven compressor for generating compressed air for the operation of air brakes and air springs. For a truck lacking an on-board air compressor, an auxiliary air compressor can be installed to service the ice/snow removal assembly. Such an auxiliary air compressor can be driven by the engine, by the vehicle's electrical system, or by a turbine driven from the vehicle's exhaust system.

In combination with using a compressed air source, an air amplifier can also be used. Air amplifiers use part of the compressed air to draw in atmospheric air, the combined volume of compressed and atmospheric air being much higher than compressed air alone. The air amplifiers can be used to inflate air bags more rapidly to reduce the time taken for a roof cleaning operation.

In one embodiment of the invention, a collar is fixed into a locally enforced region of the airbag and an air amplifier is inserted into and fixed into the collar with a flexible pipe extending between the air amplifier and the source of compressed air. The air amplifier can include an escape valve which is opened when the compressed air supply is shut off so as to allow the bag to deflate when the ice removal operation has been completed. The air amplifier is located in a part of the bag which, as the bag inflates, does not bear against either the trailer roof or the cover. In an alternative embodiment of the invention, when an air amplifier is not used or is used at a position remote from the bag, the flexible pipe is sealed directly into the collar.

The air supply assembly can include an air filter to eliminate contaminants and moisture from the air supplied to the bags and to ensure greater reliability and longer life expectancy for the air bags. The assembly can also include a regulator valve to prevent the air bags from rupturing or other damage through over-inflation.

As an alternative to a release valve and an auxiliary pump to extract air from the bags, a reversible pump is used. In one mode, the pump is used to pump air into the air bags and in the reverse mode, is used to rapidly extract air from the air bags. As an alternative to positive extraction of air, the bags are allowed to deflate automatically as the operator halts the flow of forced air into the system and proceeds to pull the cover back to its rest position.

While a flexible cover made of reflective material can be used to limit heating of the trailer, the cover can alternatively be made of a dark material to encourage absorption of sunlight to heat the trailer interior. Alternatively, particularly for trailer tops made of translucent material permitting natural light to illuminate the trailer interior, a clear cover material can be used.

As shown in FIG. 5, a series of airbags 24 are distributed along the length of the trailer, the bags located generally centrally of the trailer roof in a transverse direction, the bags in their uninflated form being generally rectangular in shape. With this form of bag, as the bags are inflated, considerable pressure may be applied to the trailer roof near the roof centre at locations furthest from the natural support provided by the trailer side and end walls. To reduce the chance of damage to the vehicle roof from the application of pressure, the bags are alternatively of long, tubular form and are located close to the trailer walls. In another alternative form as shown in FIG. 6, which is a view from above with cover removed, some air bags 24 are of I-form with cross-pieces the of the I-form located near the trailer sidewalls and with the vertical span of the I-form extending widthwise across the vehicle roof. In this particular arrangement, other air bags at the front and back of the trailer have an elongate bolster form. It will be understood that a variety of possible air bag shapes and locations are possible depending on desired pressure distribution over the roof of the trailer and the particular form desired in the flexible cover as the bags are inflated. As a further alternative to multiple bags, as shown in FIG. 7, a single bag is mounted to extend over a substantial part of the length and width of the trailer.

To further combat downward pressure on the trailer roof caused by the inflating air bags, re-enforcement can be added to the roof by, for example, adding support rods on the inside of the trailer or by locally strengthening the roof sheeting material.

As a further aid to displacing snow and ice, as shown in FIGS. 8 and 9, a rigid, light-weight plastics rod 26 is attached to the top surfaces of the bags 24 so as to extend over at least part of the trailer length underneath the cover 10. In operation, as the bags inflate, the rod 26 is driven upwards to create a more pointed profile over at least part of the length of the cover 10, so helping to break a layer of ice or snow. As an alternative to the rod 26 and as shown in FIG. 10, a smaller air bag 28 is connected to, and mounted on top of, air bag 27 with the larger bag 27 located next to the trailer roof. The bags are fed by a common compressed air supply. The smaller bag 28, once inflated, creates a relatively sharper profile in the cover 10 which helps to break up the snow and ice.

As an alternative to a cover which is flexible throughout its area, a more rigid material such as a lightweight plastic sheet material can be used over at least part of the cover area. In one embodiment, as shown by the end view of FIG. 11, a single long air bag 24 is retained in position along only one side of the trailer roof. The cover has a flexible marginal section 30 adjacent the airbag 24 and a hard plastics sheet 32 extending away from the region of the air bag to the other side of the trailer. When the bag 24 inflates, the soft section 30 conforms to the shape of the bag and protects it while the hard plastics sheet 32 rises at the bag side to create a slope towards the other side of the trailer causing the snow and ice to slide down the sloped hard plastics sheet 32 and off the roof. Once the bags are deflated, the hard plastics sheet 32 is brought back to its resting position to create a flat surface again.

As an alternative to rigid sheeting, a cover material such as fiberglass or Plexiglas™ can be used. This is of a thickness such that the cover material is not totally rigid, but is not so flexible as fully to conform to the shape of the air bags 24. As shown in FIG. 12, a cover having the form of a secondary roof has a centre section 34 of fiberglass or Plexiglas™ and marginal regions 36 of flexible material. As the bags inflate, the secondary roof adopts a dome shape as shown which causes the snow and ice to fall away. Once the bags deflate, the flexible marginal sections 36 are withdrawn to their storage position and the domed centre section 34 returns to its flat resting position against the trailer roof.

Alternative arrangements for drawing the cover 10 back into a rest position after the trailer 12 has been cleared of snow and ice are shown in FIGS. 13 to 15. After ice-clearing, it is desirable that the cover 10 is folded flat against the roof of the trailer so that it offers minimal wind resistance. The covers shown in FIGS. 13 to 15 are attached to the trailer top at their edges and have attached or integrally-formed stretchable bungee cords. A bungee cord 38 is, for example, attached at the centre line of the cover looking from front to back of the trailer as shown in FIG. 13. Alternatively, as shown in FIG. 14, two such bungee cords 38 are used, the cords being spaced from the centre line of the cover 10 except at the front and back of the trailer where the two cords converge to an anchor point 40 on the trailer.

As shown in FIG. 15, a further bridging bungee cord 42 is located inside the cover and extends between mesh cables 44 attached along the length of the cover 10 at each side. The FIG. 15 assembly has two vertically arranged air bags 24, one bag resting on the trailer roof underneath the bridging cord 42 and the other bag located above the bridging cord. As the bags deflate following snow or ice clearing, the bungee cords restore to their unstretched condition. In the course of that restoration, the bridging cord 42 draws in lower side sections of the cover 10, eventually folding these sections against the lower air bag and against the roof of the trailer. Meanwhile, the top bungee cords 38 act to draw the centre part of the cover 10 over top of the first folded part.

FIG. 16 shows an alternative embodiment of the invention in which the cover 10 is made of an elastic material whereby, when the bag 24 is inflated, the cover stretches to adopt a dome shaped profile. When the bag is subsequently deflated, the elastic cover reverts to its unstretched form. Edges of the cover are attached to the outer edges of the trailer roof with any convenient means such as a series of rings attached to the truck roof or upper side walls and a series of ties attached to the cover. In a variation of the cover design shown in FIG. 17, the cover 24 has a number of elastic material panels 46 let into the cover material to permit a localized stretching and deformation of the cover as the air bags are inflated. When the bag is deflated, the elasticated panels revert to their unstretched form so that the cover is held tightly against the trailer roof. In another variation of the cover design as shown in FIG. 18, elasticated panels 48 are fixed adjacent to the cover at various locations and the cover is made oversize in comparison with the shape and area of the trailer roof. In use, when the bags are inflated the elasticated panels stretch to accommodate the changing shape and size of the bags. When the bags are subsequently deflated, the elasticated panels return to their unstretched condition while regions 50 of the cover adjacent to the panels adopt a stored, folded configuration against the trailer roof. In each of the FIGS. 15 to 17 embodiments, the cover can be of one-piece form located on the roof of the trailer without any appreciable overhang and without the need for release or securing means to enable the air bags to be inflated and stored.

In the previously described and illustrated embodiments, the cover and the air bags form separate elements of the ice clearing assemply. This has merit in that the cover material is optimized to provide protection to the underlying air bags, while the air bag material is optimized to permit repeated inflation and deflation. In an alternative embodiment as shown in FIG. 19, the cover is integral with the air bag. Elongate air bag 52 has a top surface 54 made of elasticated material sufficiently resilient and hardwearing as not to be damaged by changes of temperature, precipitation and other harsh climate changes. The one piece bag is simply attached at its outer edges to suitable anchoring means along the edges of the trailer roof.

In the previous embodiments, the air bags are retained in position beneath the cover by a series of bungee cords or an elastic mesh net attached to the trailer roof and extending over the top of the bags. As well as operating to keep the bags in position, the cords or mesh also aid in deflating the bags.

In the prior, embodiments, the cover overlying the air bags is of one-piece form. Some trailers have sun domes or sun roofs which are opened in warm condition to permit the escape of rising hot air. To accommodate such roof formations, the cover may be formed with tailored holes and removable panels fixable by zip or Velcro™ attachment to the cover at the holes. In cool conditions, the panels fill the holes, and in warm conditions, the panels are removed or rolled back. The air bags are dimensioned and located so as not to interfere with the lighting and venting functions.

While the material of the cover is chosen to minimize the chance of snow or ice from sticking to it, the cover material can be periodically sprayed with a non-stick compound to further encourage separation and detachment of snow and ice from the cover once it has been deformed by inflating the underlying bags.

An ice layer that has built up on a trailer roof typically breaks into smaller slabs as the air bag inflates, with the slabs falling away from the bag's high point. During the operation, a safety whistle or other alarm system synchronized with the air inflation system or independently operated by the owner is actuated to signal to anyone in the vicinity of the trailer that a potentially hazardous operation is under way.

Although the invention has been described with reference to the roof of a trailer for a tractor trailer combination, the embodiments of the invention may find application in many other situations where there is an unwanted build-up of snow, ice or other adhering material. The invention is readily adaptable to vertical or inclined walls. Moreover the invention is applicable to static structures such as buildings and to other road vehicles, marine vessels, etc. 

1. Apparatus for clearing surface material, the apparatus comprising a base object, a flexible cover over the base object from which the surface material is to be cleared, a fixture means fixing the cover to the base object, and a release mechanism actuable to permit a movement of at least part of the cover from the base object, a bag lodged between the cover and the base object, the bag inflatable to cause the movement of the at least part of the cover and thereby clear the surface material.
 2. Apparatus as claimed in claim 1, the base object being of a cuboid form, the flexible cover located over an upper face of the cuboid base object.
 3. Apparatus as claimed in claim 2, the base object being one of a trailer, a truck and a building.
 4. Apparatus as claimed in claim 2, the bag extending substantially the length of the base object.
 5. Apparatus as claimed in claim 1, the flexible cover being a taupaulin.
 6. Apparatus as claimed in 1, the fixture means including a first set of anchor rings along one edge of the cover, a second set of anchor rings along a wall of the base object, a tie extending between pairs of rings of the first and second set with an end of the tie anchored at said release mechanism.
 7. Apparatus as claimed in claim 1, the fixture means including a bar extending along and attached to one edge of the cover, and a plurality of ties, each tie attached at one end to the flexible cover at respective points adjacent to the bar, the ties anchored at their distal ends to respective ones of a plurality of such release mechanisms.
 8. Apparatus as claimed in claim 1, the release mechanism including a spring movable against spring bias upon inflation of the bag to permit the movement of the flexible cover and movable under the spring bias upon a deflation of the bag to cause a reverse movement of the flexible cover.
 9. Apparatus as claimed in claim 1, the release mechanism including a spring movable against spring bias upon inflation of the bag to permit the movement of the flexible cover and movable under the spring bias to cause deflation of the bag and a reverse movement of the flexible cover.
 10. Apparatus as claimed in claim 1, having a plurality of such bags lodged between the flexible cover and the base object.
 11. Apparatus as claimed in claim 1, the base object having a wall, the bag having an elongate chamber, the bag lodged in a position in which the elongate chamber is close to and generally parallel to the wall.
 12. Apparatus as claimed in claim 1, further comprising a generally rigid member lodged between the bag and the flexible cover, the rigid member pressed against the flexible cover upon inflation of the bag to cause a profile discontinuity in the flexible cover.
 13. Apparatus as claimed in claim 1, the cover having a rigid part and a flexible part, whereby, upon inflation of the bag, a profile discontinuity develops at a junction region between the rigid part and the flexible part.
 14. Apparatus as claimed in claim 13, the rigid part being a cap and the flexible part being a wall depending from the cap.
 15. Apparatus as claims in claim 1, further comprising a compressed air generator and a conduit extending from the compressed air generator to the air inlet means formed in the bag.
 16. Apparatus as claimed in claim 15, further including an air amplifier to draw air into the conduit in response to passage of compressed air in the conduit.
 17. Apparatus as claimed in claim 15, further including an escape valve to permit escape of air from the bag upon cessation of passage of compressed air in the conduit.
 18. Apparatus as claimed in claim 1, further including a pump actuable to draw air from the bag to cause deflation thereof.
 19. Apparatus as claimed in claim 1, wherein the flexible cover over at least part of its area forms a wall of the bag.
 20. A method of clearing surface material, the method comprising preparing for clearing the surface material by storing an inflatable bag at a surface of a base object, and fixing a flexible cover over the inflatable bag and the base object by a fixture means, and subsequently clearing surface material from the flexible cover by actuating a release mechanism to permit a movement of at least part of the flexible cover from the base object, and inflating the bag to cause the movement of the at least part of the cover thereby to clear the surface material. 